Added functionality for cyclic sliding

I added some functionality to enable cyclic sliding by adding the new "transitionType" option "cycle". With this, when the last slide is reached and the "next" link is clicked, it no longer "rewinds" to the first slide but instead it moves the first slide to the end of the list and then slides to it. Of course the navigation will also be modified accordingly and it works in both directions. That way it is possible to silde in one direction infinitely. I think this is not only very handy but more or less neccesssary when implementing the slider for mobile devices and making use of swipe-events, because the user expects the slider to move in the same direction he moved it with his finger.